Along with the rapid development of digital technology, digital display devices have been upgraded continuously, and more and more people are pursuing a better display effect of a liquid crystal display panel. Currently, a thin film transistor liquid crystal display (TFT-LCD) has gradually become a mainstream product due to its advantages such as small volume, low power consumption, being free of radiation and high resolution.
Usually, in the actual application, in the case that an image is displayed by the TFT-LCD, such a phenomenon as flickering may occur. Generally, in the case of a constant voltage, liquid crystal molecules may be maintained in a certain deflection direction all the time. In the case that the liquid crystal molecules are maintained in the same deflection direction for a long period of time, the TFT-LCD may be damaged. At this time, in the case that the voltage is changed, the liquid crystal molecules cannot be recovered to their initial states. Hence, in the actual application, an alternating voltage may be applied to the liquid crystal molecules, so as to enable the liquid crystal molecules to be deflected in different directions.
Referring to FIG. 1, data lines 11 and gate lines 12 are arranged on an array substrate in such a manner as to cross each other and define subpixel units. Each subpixel unit includes a TFT 13, a first common electrode 14, a pixel electrode 15 arranged between the first common electrode 14 and the TFT 13, and a capacitor 16 formed between the pixel electrode 15 and the first common electrode 14.
In the case that the TFT 13 is in an on state, a voltage across the data line 11 is applied to the pixel electrode 15, and meanwhile a constant voltage is applied to the first common electrode 14. In the case that the voltage applied to the pixel electrode is greater than the voltage applied to the first common electrode, the liquid crystal molecules may be deflected in a forward direction. In the case that the voltage applied to the pixel electrode is smaller than the voltage applied to the first common electrode, the liquid crystal molecules may be deflected in a backward direction. In the case that the liquid crystal molecules are deflected in the forward direction to a degree different from that in the backward direction, the “flickering” phenomenon may occur.
In the related art, usually the liquid crystal molecules are driven to deflect by alternating positive and negative voltages, and they are driven by the pixel electrode to deflect at a constant frequency. FIG. 2 shows a curve of a brightness value of the pixel electrode in the case that the liquid crystal molecules are driven by the pixel electrode to deflect at a low frequency, e.g., 60 Hz. As shown in FIG. 2, an amplitude of the brightness variation for the pixel electrode is relatively large. In addition, because the liquid crystal molecules are deflected at a low frequency, the brightness value of the pixel electrode may be varied at a low frequency too. Usually, in the case that the liquid crystal molecules are deflected at a frequency less than 120 Hz, the “flickering” phenomenon may easily be observed by human eyes, and in the case that the liquid crystal molecules are deflected at a frequency greater than or equal to 120 HZ, this phenomenon may not be easily observed by human eyes.
In a word, in the related art, the liquid crystal molecules are driven by the pixel electrode to deflect at a relatively low frequency, so a serious “flickering” phenomenon may occur for the display panel and may easily be observed by human eyes.